Manufacture of vulcanized rubber and product thereof



;,Patented Oct. 23, 1928.

UNITED STATES PATENT. OFFICE.

WINFJILD SCOTT, OI AKRON, OHIO, ASSIGNOR TO THE RUIBBER SERVICE TORIES COMPN'Y, OF- AKRON, OHIO, A.

uncan- CORPORATION OF OHIO.

MANUFACTURE -VULOANIZED RUBBER AND PRODUCT" THEREOF.

No Drawing.

The present invention relates to the process of manufacturing a vulcanized rubber product by employing as an accelerator of that process a dissimilar-aryl di-subst-itutedguanidine of the type hereinafter set forth in detail. The invention will be understood from the following description and examples wherein the invention is fully explained.

Di-phenyl-guanidine and di-ortho-tolylguanidine have heretofore been described as representatives of the class of di-substitutedguanidine accelerators. While the two compounds mentioned are accelerators of the rubber vulcanization process, I have found that as a class, all di-substituted-guanidines do not possess this property, and furthermore that many of the compounds of this class that do accelerate the process mentioned, are not suificiently active as to be commercially practicable for use in this process.

The nature andtype of the radical introduced into the guanidine nucleus generally a has a profound effect upon the vulcanization acceleratin properties and the resulting compound. any of the di-substituted-guanidines are non-accelerators, some are faster was filtered. The residuum was then washed with a dilute acid such as hydrochloric acid to separate any guanidine derivative from unchanged thiourea which remained in the product. The acid solutionwas then rendered slightly alkaline by the addition there- 70 to of a suitable alkali, such as caustic soda Animation filed April 8, 1927." Serial in. 182,188.

their action in a rubber-sulphur mix than is di-phenyl-guanidine, several are'substan- 'tially the same in accelerating power, and

others have their accelerating value so impairedas to be not at all racticable for use from an acceleration standpoint.

Qne dissimilar-aryl di-substituted-guanidine which I have manufactured and the use of which I have investigated as an accelerator of the rubber vulcanization process when employed in a variety of rubber compounds is p-di-methyl-amino-phenyl-o-tolyl-guanidine. This compound has been prepared for use in the examples as are hereinafter set forth by reacting o-tolyl-mustardoil with p-amino-di-methyl-aniline to produce a thiourea and then desulphurizing the thiourea so formed.

The thiourea desired was prepared preferably by reacting substantially 149 parts (gone molecular proportion) ofo-tolyl-mustar oil with approximately 136 arts by weight (one molecular proportion of p-amino-dimethyl-aniline. The reaction that takes place v is most conveniently represented as follows:

N 'cmtNwrn N ON CHI CH;

solution and the This product, manufactured according to the process as described, has been employed as an accelerator of the rubber vulcanization process by incorporation into a number of different types 0 rubber compounds, one of which is a so-called pure gum compound. Such a stock comprise 100 parts pale crepe rubber,

5 parts zinc oxide, 3.5 parts. sulphur, v 0.5 parts p di methyl amino phenyl otolyl-guanidine.

The above compound was mixed in the usual manner and was'then vulcanized by heating portions of the stock for varying times in a press maintained under the tem perature given by forty pounds of steam pressure per square inch. The vulcanized pieces were then tested and the following results were obtained:

Modulus of elutlcity at elongation ol- Tonal Ultistrength mate 'Tlme of cure at break e] in lbs./ a? 300% 500% 700% in.

15 min. at 287 F".-- 124 220 m 2335 920% 30 min. at 287 208 428 1715 3040 855% 45 min. at 287 203 568 2480 3700 175% 100 parts pale crepe rubber,

15 parts zinc oxide,

3.25 parts sulphur, 0.5 parts accelerator.

As the accelerator there was employed p-dimethyl amino phenyl o tolyl guanidine. The stock was vulcanized by heating portions thereof for varying times in a press maintained under the temperature given by forty pounds of steam pressure per square inch. The resulting vulcanized portions were then tested and the following results were obtained:

Modulus of elasticity T at elongation ofr323 Time of cure at lpgea/k 31; l in s. 3% i 700% me I 3" Illili. at 287 F--... 159 l 361 1385 2935 i 870% 60 min. 31; 287 1 2'93 E 7442 3000 3535 s The sc leraiior hcrembciore described. has also been employed, if; a rubber compound comprising a typical tread stock. Such a stock contained 36.5 parts smoked sheet rubber,

20 parts No. 2 amber crepe rubber, 25 parts carbon black,

2 parts sulphur,

1 part of a blended mineral and vegetable oil 1 part stearie acid,

3.5 parts mineral rubber,

,11 parts zinc oxide,

0.5 parts p-di-methyl-amino-phenyl-o-tolylguanidine.

The above compound, after mixing, was then vulcanized in a press under the conditions described in the previous examples and .the vulcanized products were tested and the following results obtained:

Modulus of Basile ity at elongation Temu" Ultiammgth mate Time of cure at break p in lbs./ F I v tion 1 hr. 15 min. at 231 F-.. 1198 2000 3895 600% 1 hr. 45 min. at Z37 FL... 1343 3180 3820 655% A vulcanized product of high tensile strength is seen to result after heating for about 75 minutes under the conditons set forth.

A hard rubber stock comprising the followigg constituents has also been manufacture 20 parts No. 2 amber crepe rubber, 20 parts smoked sheet rubber,

5 parts lime, 17.5 parts zinc oxide, 27.5 .parts sulphur, 10 parts mineral rubber,

0:5 parts of the preferred accelerator set forth.

The above mix was then vulcanized by heating in a press for about 2 to 2% hours at 287 F. An excellent but rubber was thereby obtained.

The examples hereinbefore given are to be understood as illustrative only and not at all limitative of the scope of my invention. Other means of employing the preferred aecelerating compound in rubber compositions, and other means of manufacturing the particular guanidine compound deserib d are apparent to those skilled in the art to which the invention applies. Moreover, my invention is not to be understood as de endent upon the accuracy of any theories set 01th by way of explanation of the chemical changes involved in the manufacture of the accelerator described. The invention is to be considered as limited solely by the following claims attached hereto as a part of this invention wherein I intend to claim all novelty inherent in my invention as is permissible in View of the prior art.

It is apparent from the foregoing description that the compounds designated as dis similar-aryl di-substituted guanidines hereinbefore set forth as rubber vulcanization accelerators, preferably comprise guanidine derivatives wherein different aryl groups or substituted aryl groups are substituted in place of two hydrogen atoms linked to two different nitrogen atoms. Such uanidines are of an entirely different type rom those obtained by replacing two hydrogen atoms attached to the same nitrogen atom by two dissimilar groups.

What I claim is WINFIELD SCOTT. 

